戊型肝炎-口蹄疫联合疫苗的基础研究

Hepatitis E virus (HEV) causes 20 million infections annually worldwide which leads to an estimated 56600 deaths. Recent studies have shown that HEV infection in China was mainly caused by HEV genotype 4 and swine is considered as the primary host of this HEV genotype 4. On the other hand, foot-and-mouth disease virus (FMDV) causes a highly infectious disease of cloven-hoofed animals (swine) that spreads rapidly through susceptible animal populations and can lead to large-scale epidemics, causing severe economic consequences. Therefore, a combined swine vaccine against HEV and FMDV would: 1) strongly reduce the source of HEV genotype 4 and thus reduce, probably eradicate, HEV genotype 4 infections in human populations; 2) prevent on the most devastating swine diseases which is FMDV infection. In order to achieve this objective, we herein raise the first proposal for the development of combined vaccine against HEV and Foot-Mouth Disease Virus (FMDV) infections by undertaking two different approaches: firstly, by expressing a chimeric protein that contains both HEV genotype 4 and FMDV dominant neutralization epitopes; secondly，by testing immunogenicity containing different dosages of a commercially inactivated FMDV vaccine and a candidate recombinant hepatitis E vaccine. Then, we analyze the antigenicity, immunogenicity and cross-protection of the developed combined vaccines. The double protection of this HEV-FMDV combined vaccine will present an interesting cost/benefit ratio for the farmers and swine industry; and most importantly will allow an alternative and effective approach for the prevention and control of HEV infection in human population through the control of HEV in the nonhuman reservoirs.

戊型肝炎病毒(hepatitis E virus, HEV)每年造成2000万人感染，导致约56600人死亡。我国HEV感染主要由基因4型HEV引起，而猪是基因4型HEV的最主要宿主。口蹄疫病毒(foot mouth disease virus, FMDV)会引起猪等偶蹄类动物感染并在易感动物中迅速扩散，导致严重的经济损失。因此，一种针对HEV和FMDV的联合疫苗将会显著减少HEV基因4型的传染源，减少甚至根除在人群中的HEV基因4型感染，同时达到预防猪罹患具有毁灭性的口蹄疫疾病。我们在国内外首次提出针对HEV和FMDV联合疫苗的研究方案，采用基因重组技术，在大肠杆菌中表达一种含有HEV基因4型和FMDV优势中和抗原表位的嵌合蛋白，在对该蛋白充分的表征研究基础上，进行该候选联合疫苗的免疫原性、抗原性、佐剂选用、体外中和试验和动物体内病毒攻击保护试验，为申报疫苗临床试验奠定基础。

人畜共患病戊型肝炎病毒（HEV）感染在工业化国家已成为严重威胁。本研究的目的是通过设计和开发一种经济有趣的针对HEV和一种破坏性猪感染的嵌合疫苗：口蹄疫病毒（FMDV）感染，探索一种在其主要宿主（猪）中控制人畜共患病HEV的新方法。首先，我们采用计算方法对不同的HEV-FMDV嵌合蛋白进行合理有效的筛选。接下来，我们使用分子克隆技术在大肠杆菌中进一步表达和纯化所选的嵌合免疫原。最后，我们评估了候选嵌合疫苗的抗原性和免疫原性。按照这种方法，我们设计并成功制备了HEV-FMDV嵌合候选疫苗（Seq 8-P222），该疫苗在大肠杆菌中以可溶性蛋白质的形式高度过度表达，并可自组装成病毒样颗粒。此外，候选疫苗具有热稳定性，并表现出最佳的抗原性和免疫原性。这项研究为疫苗开发技术提供了新的见解，在实验之前，利用生物信息学从更大的集合中选择最佳候选疫苗。它还介绍了第一个在大肠杆菌中产生的HEV-FMDV嵌合蛋白，作为一种有希望的嵌合疫苗候选，可以参与减少人畜共患病HEV向人类的传播，同时预防猪的高度传染性口蹄疫。